Most prior grape-picking machines use practically the same principle for harvesting grapes. This is to beat or shake the vine by imparting sinusoidal or pseudo-sinusoidal motion thereto at an amplitude and at a frequency suitable for causing the grapes or the bunches of grapes to become detached. This motion is communicated to the vine via shaker or beater members disposed in such a manner as to act either on the vinestock or stem or else on the vegetation, i.e. on the fruit-bearing portion of the vine, depending on the type and number of shaker or beater members used. The percentage of bunches and/or individual grapes which are detached from the vine depends on the number and the amplitude of the oscillations to which a given bunch of grapes is subjected. The more energetic the shaking to which a given bunch of grapes is subjected, and the more frequently it is shaken, the more likely said bunch or its individual grapes is are to become detached from the vine. The number and the amplitude of the oscillations to which a given bunch of grapes is subjected depend on various parameters that may be selected, in particular on the amplitude and the frequency of the control mechanism associated with the shaker or beater members, on the length of the active zone of said shaker or beater members, on the stiffness or the flexibility thereof, and on the speed at which the machine advances, together with other factors which are imposed by the vine itself, in particular the way it is trained, its shape, and the resistance it gives to the motions of the beater or shaker members.
Simultaneously with causing bunches of grapes and individual grapes to become detached, the shaker or beater members damage the vine, at least to some extent, which may be detrimental to its health. When the shaker or beater members are designed to act on the vegetation of the vine, they generally give rise to the following types of damage:
(a) leaf stripping, thereby reducing the vine's photosynthesis activity and giving rise to difficulties in cleaning and harvesting (leaves mixed with the harvested grapes), and possibly giving rise to problems in wine-making;
(b) breaking of a large number of vine shoots, giving rise to difficulties in subsequent vine pruning;
(c) disbudding which may compromise future yield from the vine (fructification); and
(d) injuries to vine shoots that facilitate the penetration of disease.
The more energetic and the more numerous the actions of the shaker or beater members on the vegetation of a vine plant, the greater the number of occasions on which the above-mentioned damage is suffered and the greater the amount of damage on each occasion. It is therefore generally necessary to find a compromise between the various above-mentioned parameters in order to obtain an acceptable percentage of harvested grapes or bunches of grapes without giving rise to too much damage to the vine.
In a first prior art type of picking machine (see French Pat. Nos. 2 293 132, 2 313 859, 2 373 222, 2 437 769, 2 509 955 and 2 554 673, and U.S. Pat. No. 4,418,521), the shaker assembly comprises two series of more or less flexible whips or flails which are vertically spaced and with the whips or flails in each series being rigidly fixed at one of their ends to a vertical flail-carrying plate capable of being driven with oscillating motion about a vertical axis, while the opposite ends or "points" of the flails are free and constitute the active portions thereof. In this first prior art type of picking machine the whips or flails must be relatively flexible in order to adapt individually to the variations in thickness of vine vegetation. In a row of vines, each vine plant generally has vegetation whose thickness varies in a vertical direction, and at a given height the thickness of the vegetation varies from one vine plant to the next. In order to obtain good adaptability to variations in vegetation thickness, it is advantageous to use whips or flails which are highly flexible. However, the more the whips or flails are flexible, the greater the variability in the real amplitude of the motion of the flail points, and consequently the greater the variability in shaking effectiveness, whereby harvesting effectiveness varies depending on the resistance that the vine vegetation puts up against the whips or flails. If the resistance is large, then the amplitude of whip or flail point motion is practically eliminated and the shaking efficiency from the point of view of detaching grapes or bunches of grapes is nil or nearly nil. In contrast, if the resistance is low, the amplitude of whip or flail point motion is large and the shaking efficiency is improved. However, if the resistance is very low or nil, then the points of the whips or flails tend to acquire excessive amplitude and speed (the flails are said to "race"). This happens in particular when the flails move past a vine plant whose vegetation is not robust or is thin or when the whips or flails move past a space or "hole" between two successive vine plants. This gives rise to very considerable leaf stripping and to a prohibitive number of vine shoots being broken, and may even lead to a weak vine plant being completely decapitated together with a portion of the immediately following vine plant. That is why it is normally necessary to use whips or flails which are semi-rigid or semi-flexible.
Further, in this first prior art type of picking machine, the whips or flails are relatively short (about one meter (m) long), such that their active portions in the vicinity of the whip or flail points are likewise short. Several solutions may be adopted in order to ensure that a given bunch of grapes is shaken a sufficient number of times to ensure that it is detached from the vine. A first solution naturally consists in increasing the frequency at which the flail-controlling mechanism oscillates, however this increases the speed of the flail points and increases the above-mentioned drawbacks which are related to high speed and large amplitude motion of the flail points when they encounter little resistance from the vegetation. A second solution consists in reducing the speed at which the picking machine moves forwards, however that increases the time required for picking. A third solution consists in increasing the length of the active flail zones by using flails which are longer and which are bent, with the facing active portions thereof being substantially mutually parallel (see French Pat. Nos. 2 313 859, 2 509 955, and 2,554,673, and U.S. Pat. No. 4,418,521 ). However, the amount by which the active portions of the flails can be lengthened is highly limited, in particular because of the mechanical behavior of the flails. A fourth solution consists in providing two successive sets of shakers (see for example French Pat. No. 2 293 132 and U.S. Pat. No. 4,418,52). However, this solution is relatively expensive (the machine chassis is longer and two sets of shakers and control mechanisms are associated therewith).
It is clear from the above, that in order to obtain flails or whips which adapt well to variations in the thickness of vine plant vegetation, both in the vertical direction up the vine plants and in the longitudinal direction along the rows of vines, and in order to obtain a high percentage of harvested fruit in a short period of time per unit cultivated area with a minimum of damage to the vines, the choices to be made between the various construction and operating parameters of prior art picking machines of the first type described above are difficult and can at best result in a compromise only.
In a second type of prior art picking machine (French Pat. Nos. 2 516 742 and 2 522 246), each beater in each of two sets of beaters is constituted by a metal rod of the piano wire type, with both ends of the rods being fixed rigidly to a frame-shaped vertical and longitudinal support, with one frame being provided for each series of beaters, and with each support being hinged to the chassis of the machine about a vertical axis which is situated close to one of its ends (French Pat. No. 2 516 742) or else which is movably mounted on the chassis by means for maintaining the two support frames permanently in mutually parallel positions as they perform oscillating motion (French Pat. No. 2 522 246). A reciprocating motion drive device is connected to each of the two support frames to cause them to oscillate about a mean position. Since both support frames are rigid and since the beaters have both ends rigidly fixed to the support frames, the speed of beater displacement and the real amplitude of their motion are both well controlled and correspond to the speed and amplitude of the reciprocating motion drive devices associated with the support frames. As a result, when vine vegetation puts up little resistance to the beaters, the beaters do not tend to "race", and under such conditions prior art picking machines of this second type give rise to considerably less damage to the vines than that caused by picking machines of the first type whose shaker members are constituted by relatively flexible whips or flails each having one end free. In addition, for identical amplitude of motion, at identical frequency of oscillation, and at identical speed of machine advance, because of the relatively long active portions of the beaters, they have an effect on each bunch of grapes which lasts longer than would be the case with prior art picking machines of the first type, which therefore makes it theoretically possible to increase the percentage of harvested fruit. However, although the beaters are intended to be made of piano wire, their capabilities in elastic deformation and consequently their capabilities in adapting to variations in thickness of vine vegetation or in the machine being misaligned relative to a row of vines are relatively poor. This is so much the case that in French Pat. No. 2 516 742 provision is made for each support frame to be fixed to the bottom end of a vertical arm whose top end is hinged to the chassis of the machine about both a horizontal axis and a longitudinal axis with each arm being returned to a vertical position by the combined effect of a mass and a spring. With such an assembly, the two series of beaters move away from each other and towards each other automatically as a function of varying thickness of vine vegetation as the machine moves along a row of vines. However this adaptation of the gap between the two series of beaters to the variation in the thickness of the vegetation is performed simultaneously by all of the beaters in each series. Consequently, when the beaters pass a vine plant whose vegetation varies considerably in thickness in the vertical direction, the gap between the two series of beaters adjusts automatically to the thickest portion of the vegetation on the vine plant. As a result, the beaters level with the thinner portions of the vegetation have little or no effect on these portions of the vegetation and only a small quantity of the grapes thereon are harvested, if any. As a result, it happens in practice and under identical operating conditions that prior art picking machines of the second type do not obtain a subsantially higher percentage of harvested fruit than can be obtained with prior art grape picking machines of the first type.
In a third type of prior art grape picking machine (French Pat. Nos. 2 417 247, 2 417 248 and 2 515 926, and U.S. Pat. Nos. 4,286,426 and 4,432,190), two substantially ski-shaped shaker members are provided each having a relatively long rectilinear portion and each having a sloping or curved portion at each end extending sideways out from the machine. The speed and the real amplitude of shaker member motion are well controlled and correspond to the speed and amplitude of the reciprocating motion drive devices associated with the shaker members. However, since the shaker members are very rigid, have relatively long active portions, and act on the top portions of the vine stocks, they run the risk of damaging said vine stocks by prolonged rubbing thereagainst. Further, they run the risk of uprooting a vine stock that happens to be particularly robust and rigid. Further, such a shaking system is effective only for those types of vine in which the fruit-bearing zone is located essentially in a narrow zone measured in the vertical direction and situated near to the top portion of the vine stock. It is not at all appropriate for cases where the fruit-bearing zone extends over a considerable height which may run from a few centimeters above the ground to a considerable distance (sometimes more than a meter) above the trunk or stock of the vine.
The main object of the present invention is to provide a machine for harvesting fruits and berries and the like, the machine having rod-shaped shaker members which are capable of adapting individually to variations in the thickness of the vegetation of the fruit trees or bushes as in the case of prior art picking machines of the first type having whips or flails, but in which the speed and the real amplitude of motion of the active portions are well controlled so that the shaking is effective even at relatively low frequencies of oscillation and regardless of the resistance put up by the vegetation, and so that the active portions of the rods do not have any tendency to "race" and to damage the fruit trees or bushes when their vegetation puts up low resistance.
The present invention also seeks to provide a harvesting machine in which the rod-shaped shaker members have active portions of considerably greater length than the active portions of the whips or flails of prior art picking machines of the first type, without a corresponding increasing in the speed and in the real amplitude of motion of the active portions of the rods, which increase in prior art machines having whips or flails gives rise to problems of flail mechanical performance and of increased damage to fruit trees and bushes.